Post-translational modifications of histone proteins, such as acetylation, methylation, and phosphorylation, play essential roles in regulating chromatin dynamics. The mono-, di-, or tri-methylated peptides can be used to study the protein-protein interactions. The peptide methylation occurs at arginine or lysine residues, resulting in methyl-arginine or methyl-lysine. In a new study, an H3 histone tail mimicking peptides were used to bind with the ASHHH2 CW domain.The monomethylated ARTK(me1)QTARY, dimethylated ARTK(me2)QTARY, and trimethylated ART- K(me3)QTARY were synthesized by LifeTein
(95% purity by mass spectrometry).
Methylated Peptides and Histone Methylation
The methylated peptide is an important tool to study the histone methylation. Histone methylation can be associated with either transcriptional repression or activation. There is an emerging realization that DNA and histone lysine methylation in mammals are highly interrelated. Targeting of DNA methylation is mechanistically linked to H3K9 methylation. For example, the p53 gene is the most frequently mutated tumor suppressor gene in human cancers. Upon genotoxic stresses, p53 proteins are activated in the setting of multiple post-translational modifications such as phosphorylation, methylation and acetylation for full activation. The arginine methylation includes Arg(Me), Arg(Me)2 asymmetrical or Arg(Me)2 symmetrical.
The therapeutic monoclonal antibody cetuximab is among the latest arsenal developed for war on cancer, designed to block tumor growth by specifically targeting the extracellular domain of EGFR on the surface of cancer cells. Alarmingly, resistance to cetuximab has been observed. Using peptides containing methylated arginine residues synthesized by LifeTein to generated specific antibodies in mice, the researchers were able to pinpoint Arg198 and Arg200 of EGFR were methylated by protein arginine methyltransferase 1 (PRMT1) in colorectal cancer cells, which could be critical for cetuximab resistance. Their results paved a way for developing better treatment for cancer patients.